import {indexOf} from "../util/misc.js"

// Find the line object corresponding to the given line number.
export function getLine(doc, n) {
    n -= doc.first
    if (n < 0 || n >= doc.size) throw new Error("There is no line " + (n + doc.first) + " in the document.")
    let chunk = doc
    while (!chunk.lines) {
        for (let i = 0; ; ++i) {
            let child = chunk.children[i], sz = child.chunkSize()
            if (n < sz) {
                chunk = child;
                break
            }
            n -= sz
        }
    }
    return chunk.lines[n]
}

// Get the part of a document between two positions, as an array of
// strings.
export function getBetween(doc, start, end) {
    let out = [], n = start.line
    doc.iter(start.line, end.line + 1, line => {
        let text = line.text
        if (n == end.line) text = text.slice(0, end.ch)
        if (n == start.line) text = text.slice(start.ch)
        out.push(text)
        ++n
    })
    return out
}

// Get the lines between from and to, as array of strings.
export function getLines(doc, from, to) {
    let out = []
    doc.iter(from, to, line => {
        out.push(line.text)
    }) // iter aborts when callback returns truthy value
    return out
}

// Update the height of a line, propagating the height change
// upwards to parent nodes.
export function updateLineHeight(line, height) {
    let diff = height - line.height
    if (diff) for (let n = line; n; n = n.parent) n.height += diff
}

// Given a line object, find its line number by walking up through
// its parent links.
export function lineNo(line) {
    if (line.parent == null) return null
    let cur = line.parent, no = indexOf(cur.lines, line)
    for (let chunk = cur.parent; chunk; cur = chunk, chunk = chunk.parent) {
        for (let i = 0; ; ++i) {
            if (chunk.children[i] == cur) break
            no += chunk.children[i].chunkSize()
        }
    }
    return no + cur.first
}

// Find the line at the given vertical position, using the height
// information in the document tree.
export function lineAtHeight(chunk, h) {
    let n = chunk.first
    outer: do {
        for (let i = 0; i < chunk.children.length; ++i) {
            let child = chunk.children[i], ch = child.height
            if (h < ch) {
                chunk = child;
                continue outer
            }
            h -= ch
            n += child.chunkSize()
        }
        return n
    } while (!chunk.lines)
    let i = 0
    for (; i < chunk.lines.length; ++i) {
        let line = chunk.lines[i], lh = line.height
        if (h < lh) break
        h -= lh
    }
    return n + i
}

export function isLine(doc, l) {
    return l >= doc.first && l < doc.first + doc.size
}

export function lineNumberFor(options, i) {
    return String(options.lineNumberFormatter(i + options.firstLineNumber))
}
